This invention relates generally to a semiconductor structure and to method of making the same and more particularly to a structure including inset regions.
Various methods have been employed for forming junctions in semiconductor substrates. Perhaps the most common method has been to form on predetermined areas of a surface of the body a layer containing impurities and then heating the body to cause the impurities to diffuse inwardly into the body under said area. Another method has been to form alloy junctions. A further method has been to prediffuse impurities on surface areas of the body, etching said surface to remove loose impurities and any glass which may be formed leaving the diffusion of impurities and subsequently subjecting the wafer to a high temperature whereby the impurities are diffused further into the body to form inset regions.
In U.S. Pat. No. 3,281,291 there is described a process in which impurities are deposited on the selected surfaces of the wafer by forming a silicon oxide layer containing the impurities and then heating the wafer to diffuse the impurities from the oxide layer into the wafer. In this method the total surface of the semiconductor body is covered with the silicon oxide layer containing the impurities. There is no provision for preventing out-gasing of the impurities. There is no suggestion of forming regions of predetermined area.